import java.util.*;
class Example2_5 {
  public static void main (String args[]){
    int start = 0,end,middle;
    int a[] = {12,45,67,89,123,-45,67,20165231};
    int N = a.length;
    for(int i=0;i<N;i++){ //选择法排序数组
    for(int j=i+1;j<N;j++){
      if(a[j]<a[i]){
        int t=a[j];
        a[j]=a[i];
        a[i]=t;
      }
    }
  }
   Scanner scanner = new Scanner(System.in);
   System.out.println("输入证书，程序判断该整数是否在数组中");
   int number = scanner.nextInt();
   int count = 0;
   end = N;
   middle=(start+end)/2;
   while(number!=a[middle]){
     if(number>a[middle])
     start=middle;
     else if(number<a[middle])
     end = middle;
     middle = (start+end)/2;
     count++;
     if(count>N/2)
     break;
   }
   if (count>N/2)
     System.out.printf("%d不在数组中.\n",number);
   else
     System.out.printf("%d在数组中.\n",number);
  }
}
